A reliable way to make a brick tower
Instead of two empties use one curve and an empty as follows :


add a curve circle
add  Array modifier with some offset ( 1.05) and set it to fit curve
add a curve modifier and set to use the curve circle
add Array modifier with the empty as an offset object
this is the setup now :




and the modifiers ( on the brick ) :



the result and manipulation :

all object should be at the origin, sclale the curve to change the diamater , and rotate the empty to create the rotation offset





update : for any wall shape : 


add a stack of 3 array modifiers and one curve modifier as follows  :




You control the length and shape of the wall using the curve :